1：Experimental Design and Method Selection

The p-Si nanowires were prepared by metal-assisted chemical etching for enhanced optical absorption and decorated with a mesoporous α-Fe2O3 thin film (~80 nm) through pyrolysis of ferrocene. A thin carbon passivation layer (~20 nm) was further deposited through ion sputtering.

2：Sample Selection and Data Sources

Boron-doped P-Type silicon wafers (resistivity of 0.01?1 Ω cm) with crystal orientation of (100) were used.

3：List of Experimental Equipment and Materials

Tube furnace (KJMTI, OTF-1200X, China), Ion Sputter & Coating Unit (HITACHI, E-1045), X-ray diffraction (XRD, Ultima IV, Rigaku Co., LTD, Japan Cu K, = 1.54178 ?), Raman spectrometer (LabRAM HR Evolution), field-emission scanning electron microscope (FESEM, FEI, Sirion 200), reflectance UV–vis spectrometer (UV-3600, SHIMADZU), X-ray photoelectron spectroscopic (XPS) properties were measured on a Kratos AXIS Ultra DLD spectrometer, Kelvin Probe Force Microscopy (KPFM) measurement was performed in the lift mode of Bruker Multimode 8.

4：Experimental Procedures and Operational Workflow

The Si NW samples were fixed on the top of a crucible loaded with ferrocene and annealed at 550°C for 2 h in a tube furnace. The samples were further put into the Ion Sputter & Coating Unit to deposit a ～20 nm carbon layer.

5：Data Analysis Methods

The crystallographic structures of the as-prepared samples were identified by XRD. The crystalline phases were confirmed by Raman spectrometer. The morphologies of the samples were observed using FESEM. The absorption test of the samples was conducted by using a reflectance UV–vis spectrometer. The XPS properties were measured on a Kratos AXIS Ultra DLD spectrometer. KPFM measurement was performed in the lift mode of Bruker Multimode 8.